Question

我是python的初学者，这个作业要求我获得投资的未来价值。

p = raw_input("[How much did you invest?]:")
r = str(raw_input("[How much is the interest rate?]:"))
n = raw_input("[How long have you been investing?]:")
future_value = p*(1+1)**n
print "\n\n\tYour future value of your investment is: %s\n" % future_value

错误代码：

unsupported operand type(s) for ** or pow(): 'int' and 'str'

任何帮助？

Answer 1

您需要将输入转换为int，因为raw_input函数返回string

如果在交互式终端中键入help(raw_input)，您应该看到定义：

raw_input(...)
    raw_input([prompt]) -> string

固定代码：

p = int(raw_input("[How much did you invest?]:"))
r = float(raw_input("[How much is the interest rate?]:"))
n = int (raw_input("[How long have you been investing?]:"))
future_value = p*(1+1)**n
print "\n\n\tYour future value of your investment is: %s\n" % future_value

Answer 2

错误消息告诉您正在尝试将整数提升为字符串幂。那必须是代码的这一部分：

(1+1)**n

确实，1 + 1是一个整数（它是2 - 如果你想要2，为什么不写2而不是1+1？）。

那是什么n？ n来自raw_input()来电。实际上，raw_input()总是返回一个字符串。如果您想将该字符串更改为整数（您这样做），请改为：

n = int(raw_input("[How long have you been investing?]:"))

代码错误 - Python中的未来投资价值

2 个答案: